Chapter 4
Introduction
This chapter discusses general planning and conduct of
instrument approaches by pilots operating under Title 14 of
the Code of Federal Regulations (14 CFR) Parts 91,121, 125,
and 135. The operations specifications (OpSpecs), standard
operating procedures (SOPs), and any other FAA- approved
documents for each commercial operator are the final
authorities for individual authorizations and limitations as
they relate to instrument approaches. While coverage of
the various authorizations and approach limitations for all
operators is beyond the scope of this chapter, an attempt
is made to give examples from generic manuals where it
is appropriate.
Approaches
Approach Planning
Depending on speed of the aircraft, availability of weather
information, and the complexity of the approach procedure
or special terrain avoidance procedures for the airport
of intended landing, the in-flight planning phase of an
instrument approach can begin as far as 100-200 NM from
the destination. Some of the approach planning should
be accomplished during preflight. In general, there are
five steps that most operators incorporate into their flight
standards manuals for the in-flight planning phase of an
instrument approach:
• Gathering weather information, field conditions,
and Notices to Airmen (NOTAMs) for the airport of
intended landing.
• Calculation of performance data, approach speeds,
and thrust/power settings.
• Flight deck navigation/communication and
automation setup.
• Instrument approach procedure (IAP) review and, for
flight crews, IAP briefing.
• Operational review and, for flight crews, operational
briefing.
Although often modified to suit each individual operator,
these five steps form the basic framework for the in-flight
planning phase of an instrument approach. The extent of
detail that a given operator includes in their SOPs varies
from one operator to another; some may designate which
pilot performs each of the above actions, the sequence, and
the manner in which each action is performed. Others may
leave much of the detail up to individual flight crews and
only designate which tasks should be performed prior to
commencing an approach. Flight crews of all levels, from
single-pilot to multi-crewmember Part 91 operators, can
benefit from the experience of commercial operators in
developing techniques to fly standard instrument approach
procedures (SIAPs).
Determining the suitability of a specific IAP can be a very
complex task, since there are many factors that can limit
the usability of a particular approach. There are several
questions that pilots need to answer during preflight
planning and prior to commencing an approach. Is the
approach procedure authorized for the company, if Part
91, subpart K, 121, 125, or 135? Is the weather appropriate
for the approach? Is the aircraft currently at a weight that
will allow it the necessary performance for the approach
and landing or go around/ missed approach? Is the aircraft
properly equipped for the approach? Is the flight crew
qualified and current for the approach? Many of these types
of issues must be considered during preflight planning and
within the framework of each specific air carrier’s OpSpecs,
or Part 91.
Weather Considerations
Weather conditions at the field of intended landing dictate
whether flight crews need to plan for an instrument
approach and, in many cases, determine which approaches
can be used, or if an approach can even be attempted. The
gathering of weather information should be one of the first
steps taken during the approach-planning phase. Although
there are many possible types of weather information,
the primary concerns for approach decision-making are
windspeed, wind direction, ceiling, visibility, altimeter
setting, temperature, and field conditions. It is also a good
idea to check NOTAMs at this time, in case there were any
changes since preflight planning.
Windspeed and direction are factors because they often
limit the type of approach that can be flown at a specific
location. This typically is not a factor at airports with
multiple precision approaches, but at airports with only a
few or one approach procedure, the wrong combination
of wind and visibility can make all instrument approaches
at an airport unavailable. Pilots must be prepared to
execute other available approaches, not just the one that
they may have planned for. As an example, consider the
available approaches at the Chippewa Valley Regional
Airport (KEAU) in Eau Claire, Wisconsin. [Figure 4-1] In the
event that the visibility is reported as less than one mile,
the only useable approaches for Category C aircraft is the
Instrument Landing System (ILS) and Lateral navigation
(LNAV)/vertical navigation (VNAV) to Runway 22. This
leaves very few options for flight crews if the wind does not
favor Runway 22; and, in cases where the wind restricts a
landing on that runway altogether, even a circling approach
cannot be flown because of the visibility.
Weather Sources
Most of the weather information that flight crews receive
is issued to them prior to the start of each flight segment,
but the weather used for in-flight planning and execution
of an instrument approach is normally obtained en route
via government sources, company frequency, or Aircraft
Communications Addressing and Reporting System
(ACARS).
Air carriers and operators certificated under the provisions
of Part 119 (Certification: Air Carriers and Commercial
Operators) are required to use the aeronautical weather
information systems defined in the OpSpecs issued to that
certificate holder by the FAA. These systems may use basic
FAA/National Weather Service (NWS) weather services,
contractor or operator-proprietary weather services, and/
Figure 4-1. Chippewa Regional Airport (KEAU), Eau Claire, Wisconsin.
or Enhanced Weather Information System (EWINS) when
approved in the OpSpecs. As an integral part of EWINS
approval, the procedures for collecting, producing, and
disseminating aeronautical weather information, as well
as the crewmember and dispatcher training to support
the use of system weather products, must be accepted or
approved.
Operators not certificated under the provisions of 14
CFR Part 119 are encouraged to use FAA/NWS products
through the Flight Service Stations (FSS). FSS provide pilot
weather briefings, en route weather, receive and process
instrument flight rule (IFR) and visual flight rule (VFR) flight
plans, relay air traffic control (ATC) clearances, and issue
NOTAMs. They also provide assistance to lost aircraft and
aircraft in emergency situations and conduct VFR search
and rescue services.
Direct User Access Terminal System (DUATS), funded by the
FAA, allows any pilot to access weather information and file
a flight plan via computer. Two contract vendors currently
provide information services within the DUATS system,
and can be accessed via the Internet at www.duats.com
or www.1800wxbrief.com. The current vendors of DUATS
II service and the associated phone numbers are listed in
Chapter 7 of the Aeronautical Information Manual (AIM).
Flight Information Service—Broadcast (FIS-B) provides
certain aviation weather and other aeronautical information
to aircraft equipped with an appropriate flight deck display.
Reception of FIS-B services can be expected within a
ground station coverage volume when line-of-sight
geometry is maintained between the aircraft and ground
station. National Airspace System (NAS) wide service
availability was targeted for 2013 and is currently available
within certain regions. FIS-B provides the following textual
and graphical aviation weather and aeronautical products
free-of-charge. A detailed description of these products
can be found in the AIM.
• Aviation Digital Data Services (ADDS) provides the
aviation community with text, digital and graphical
forecasts, analyses, and observations of aviation
related weather variables. ADDS is a joint effort of
National Oceanic and Atmospheric Administration’s
(NOAA) Earth System Research Laboratory, National
Center for Atmospheric Research (NCAR) Research
Applications Laboratory (RAL), and the Aviation
Weather Center (AWC).
• Hazardous In-flight Weather Advisory Service
(HIWAS) is a national program for broadcasting
hazardous weather information continuously over
selected navigation aids (NAVAIDs). The broadcasts
include advisories such as Airman’s Meteorological
Information (AIRMETs), Significant Meteorological
Information (SIGMETs), convective SIGMETs, and
urgent pilot weather reports (PIREPs/UUA). These
broadcasts are only a summary of the information,
and pilots should contact an FSS for detailed
information.
• Telephone Information Briefing Service (TIBS)
is a service prepared and disseminated by
Flight Service. It provides continuous telephone
recordings of meteorological and aeronautical
information. Specifically, TIBS provides area and
route briefings, as well as airspace procedures and
special announcements, if applicable. It is designed
to be a preliminary briefing tool and is not intended
to replace a standard briefing from a flight service
specialist. The TIBS service is available 24 hours a day
and is updated when conditions change, but it can
only be accessed by a touch tone phone. The phone
numbers for the TIBS service are listed in the Chart
Supplement, formerly the Airport/Facility Directory
(A/FD). TIBS should also contain, but is not limited to:
surface observations, terminal aerodrome forecast
(TAFs), and winds/temperatures aloft forecasts.
The suite of available aviation weather product types
is expanding with the development of new sensor
systems, algorithms, and forecast models. The FAA and
NWS, supported by the NCAR and the NOAA Forecast
Systems Laboratory (FSL), develop and implement new
aviation weather product types through a comprehensive
process known as the Aviation Weather Technology
Transfer process. This process ensures that user needs
and technical and operational readiness requirements are
met as experimental product types mature to operational
application.
The development of enhanced communications
capabilities, most notably the internet, has allowed pilots
access to an increasing range of weather service providers
and proprietary products. It is not the intent of the FAA to
limit operator use of this weather information. However,
pilots and operators should be aware that weather services
provided by entities other than the FAA, NWS, or their
contractors (such as the DUATS and flight information
services data link (FISDL) providers) may not meet FAA/
NWS quality control standards.
Broadcast Weather
The most common method used by flight crews to obtain
specific in-flight weather information is to use a source that
broadcasts weather for the specific airport. Information
about ceilings, visibility, wind, temperature, barometric
pressure, and field conditions can be obtained from most
types of broadcast weather services. Broadcast weather
can be transmitted to the aircraft in radio voice format or
digital format, if it is available, via an ACARS system.
Automated Terminal Information Service (ATIS)
Automatic terminal information service (ATIS) is the
continuous broadcast of recorded non-control information
in selected high activity terminal areas. Its purpose is to
improve controller effectiveness and to relieve frequency
congestion by automating the repetitive transmission
of essential but routine information. The information is
continuously broadcast over a discrete very high frequency
(VHF) radio frequency or the voice portion of a local NAVAID.
ATIS transmissions on a discrete VHF radio frequency are
engineered to be receivable to a maximum of 60 NM from
the ATIS site and a maximum altitude of 25,000 feet above
ground level (AGL). At most locations, ATIS signals may be
received on the surface of the airport, but local conditions
may limit the maximum ATIS reception distance and/or
altitude. Pilots are urged to cooperate in the ATIS program
as it relieves frequency congestion on approach control,
ground control, and local control frequencies. The CS
indicates airports for which ATIS is provided.
ATIS information includes the time of the latest weather
sequence, ceiling, visibility, obstructions to visibility,
temperature, dew point (if available), wind direction
(magnetic), velocity, altimeter, other pertinent remarks,
instrument approach and runway in use. The ceiling/sky
condition, visibility, and obstructions to vision may be
omitted from the ATIS broadcast if the ceiling is above
5,000 feet and the visibility is more than five miles. The
departure runway will only be given if different from the
landing runway except at locations having a separate ATIS
for departure. The broadcast may include the appropriate
frequency and instructions for VFR arrivals to make initial
contact with approach control. Pilots of aircraft arriving or
departing the terminal area can receive the continuous
ATIS broadcast at times when flight deck duties are least
pressing and listen to as many repeats as desired. ATIS
broadcast will be updated upon the receipt of any official
hourly and special weather. A new recording will also be
made when there is a change in other pertinent data, such
as runway change and instrument approach in use.
Automated Weather Observing Programs
Automated weather reporting systems are increasingly
being installed at airports. These systems consist of
various sensors, a processor, a computer-generated voice
subsystem, and a transmitter to broadcast local, minute
by-minute weather data directly to the pilot.
Automated Weather Observing System
The automated weather observing system (AWOS)
observations include the prefix “AUTO” to indicate that
the data are derived from an automated system. Some
AWOS locations are augmented by certified observers who
provide weather and obstruction to vision information in
the remarks of the report when the reported visibility is
less than seven miles. These sites, along with the hours of
augmentation, are published in the CS. Augmentation
is identified in the observation as “OBSERVER WEATHER. ”
The AWOS wind speed, direction and gusts, temperature,
dew point, and altimeter setting are exactly the same as
for manual observations. The AWOS also reports density
altitude when it exceeds the field elevation by more than
1,000 feet. The reported visibility is derived from a sensor
near the touchdown of the primary instrument runway.
The visibility sensor output is converted to a visibility value
using a 10-minute harmonic average. The reported sky
condition/ ceiling is derived from the ceilometer located
next to the visibility sensor. The AWOS algorithm integrates
the last 30 minutes of ceilometer data to derive cloud layers
and heights. This output may also differ from the observer
sky condition in that the AWOS is totally dependent upon
the cloud advection over the sensor site.
Automated Surface Observing System (ASOS)/
Automated Weather Sensor System (AWSS)
The automated surface observing system (ASOS)/
automated weather sensor system (AWSS) is the primary
surface weather observing system of the United States. The
program to install and operate these systems throughout
the United States is a joint effort of the NWS, the FAA, and
the Department of Defense (DOD). AWSS is a follow-on
program that provides identical data as ASOS. ASOS/AWSS
is designed to support aviation operations and weather
forecast activities. The ASOS/ AWSS provides continuous
minute-by-minute observations and performs the basic
observing functions necessary to generate a aviation
routine weather report (METAR) and other aviation weather
information. The information may be transmitted over a
discrete VHF radio frequency or the voice portion of a local
NAVAID. ASOS/AWSS transmissions on a discrete VHF radio
frequency are engineered to be receivable to a maximum of
25 NM from the ASOS/AWSS site and a maximum altitude
of 10,000 feet AGL.
At many locations, ASOS/AWSS signals may be received
on the surface of the airport, but local conditions may
limit the maximum reception distance and/or altitude.
While the automated system and the human may differ
in their methods of data collection and interpretation,
both produce an observation quite similar in form and
content. For the objective elements, such as pressure,
ambient temperature, dew point temperature, wind, and
precipitation accumulation, both the automated system
and the observer use a fixed location and time-averaging
technique. The quantitative differences between the
observer and the automated observation of these elements
are negligible. For the subjective elements; however,
observers use a fixed time (spatial averaging technique) to
describe the visual elements (sky condition, visibility, and
present weather, etc.), while the automated systems use
a fixed location and time averaging technique. Although
this is a fundamental change, the manual and automated
techniques yield remarkably similar results within the limits
of their respective capabilities.
The use of the aforementioned visibility reports and
weather services are not limited for Part 91 operators.
Part 121 and 135 operators are bound by their individual
OpSpecs documents and are required to use weather
reports that come from the NWS or other approved
sources. While all OpSpecs are individually tailored, most
operators are required to use ATIS information, runway
visual range (RVR) reports, and selected reports from
automated weather stations. All reports coming from an
AWOS-3 station are usable for Part 121 and 135 operators.
Each type of automated station has different levels of
approval as outlined in individual OpSpecs. Ceiling and
visibility reports given by the tower with the departure
information are always considered official weather, and
RVR reports are typically the controlling visibility reference.
Refer to Chapter 1, Departures, of this manual, as well as
the AIM section 7-1-12 for further description of automated
weather systems.
Center Weather Advisories (CWA)
Center weather advisories (CWAs) are unscheduled inflight,
flow control, air traffic, and aircrew advisories. By nature of
its short lead time, the CWA is not a flight planning product.
It is generally a nowcast for conditions beginning in the
next two hours. CWAs will be issued:
1. As a supplement to an existing SIGMET, convective
SIGMET, or AIRMET.
2. When an in-flight advisory has not been issued
but observed or expected weather conditions
meet SIGMET/AIRMET criteria based on current
pilot reports and reinforced by other sources
of information about existing meteorological
conditions.
3. When observed or developing weather conditions
do not meet SIGMET, convective SIGMET, or
AIRMET criteria (e.g., in terms of intensity or area
coverage), but current pilot reports or other
weather information sources indicate that existing
or anticipated meteorological phenomena will
adversely affect the safe and efficient flow of air
traffic within the ARTCC area of responsibility.
Weather Regulatory Requirements
There are many practical reasons for reviewing weather
information prior to initiating an instrument approach.
Pilots must familiarize themselves with the condition of
individual airports and runways so that they may make
informed decisions regarding fuel management, diversions,
and alternate planning. Because this information is critical,
14 CFR requires pilots to comply with specific weather
minimums for planning and execution of instrument flights
and approaches..
Weather Requirements and Part 91 Operators
According to 14 CFR Part 91, § 91.103, the pilot in command
(PIC) must become familiar with all available information
concerning a flight prior to departure. Included in this
directive is the fundamental basis for pilots to review
NOTAMs and pertinent weather reports and forecasts
for the intended route of flight. This review should
include current weather reports and terminal forecasts
for all intended points of landing and alternate airports.
In addition, a thorough review of an airport’s current
weather conditions should always be conducted prior
to initiating an instrument approach. Pilots should also
consider weather information as a planning tool for fuel
management.
For flight planning purposes, weather information must be
reviewed in order to determine the necessity and suitability
of alternate airports. For Part 91 operations, the 600-2 and
800-2 rule applies to airports with precision and non-
precision approaches, respectively. Approaches with
vertical guidance (APV) are non-precision approaches
because they do not meet the International Civil Aviation
Organization (ICAO) Annex 10 standards for a precision
approach. (See Final Approach Segment section later in this
chapter for more information regarding APV approaches.)
Exceptions to the 600-2 and 800-2 alternate minimums are
listed in the front of the Aeronautical Information Services
in the Terminal Procedures Publication (TPP) and are
indicated by a symbol A on the approach charts for the
airport. This does not preclude flight crews from initiating
instrument approaches at alternate airports when the
weather conditions are below these minimums. The 600
2 and 800-2 rules, or any exceptions, only apply to flight
planning purposes, while published landing minimums
apply to the actual approach at the alternate.
Weather Requirements and Part 135 Operators
Unlike Part 91 operators, Part 135 operators may not depart
for a destination unless the forecast weather there will
allow an instrument approach and landing. According to
14 CFR Part 135, § 135.219, flight crews and dispatchers
may only designate an airport as a destination if the latest
weather reports or forecasts, or any combination of them,
indicate that the weather conditions will be at or above IFR
landing minimums at the estimated time of arrival (ETA).
This ensures that Part 135 flight crews consider weather
forecasts when determining the suitability of destinations.
Departures for airports can be made when the forecast
weather shows the airport will be at or above IFR minimums
at the ETA, even if current conditions indicate the airport to
be below minimums. Conversely, 14 CFR Part 135, § 135.219
prevents departures when the first airport of intended
landing is currently above IFR landing minimums, but the
forecast weather is below those minimums at the ETA.
Another very important difference between Part 91
and Part 135 operations is the Part 135 requirement for
airports of intended landing to meet specific weather
criteria once the flight has been initiated. For Part 135,
not only is the weather required to be forecast at or
above instrument flight rules (IFR) landing minimums for
planning a departure, but it also must be above minimums
for initiation of an instrument approach and, once the
approach is initiated, to begin the final approach segment
of an approach. 14 CFR Part 135, § 135.225 states that pilots
may not begin an instrument approach unless the latest
weather report indicates that the weather conditions are
at or above the authorized IFR landing minimums for that
procedure. 14 CFR Part 135, § 135.225 provides relief from
this rule if the aircraft has already passed the final approach
fix (FAF) when the weather report is received. It should be
noted that the controlling factor for determining whether
or not the aircraft can proceed is reported visibility. RVR, if
available, is the controlling visibility report for determining
that the requirements of this section are met. The runway
visibility value (RVV), reported in statute miles (SM), takes
precedent over prevailing visibility. There is no required
timeframe for receiving current weather prior to initiating
the approach.
Weather Requirements and Part 121 Operators
Like Part 135 operators, flight crews and dispatchers
operating under Part 121 must ensure that the appropriate
weather reports or forecasts, or any combination thereof,
indicate that the weather will be at or above the authorized
minimums at the ETA at the airport to which the flight is
dispatched (14 CFR Part 121, § 121.613). This regulation
attempts to ensure that flight crews will always be able to
execute an instrument approach at the destination airport.
Of course, weather forecasts are occasionally inaccurate;
therefore, a thorough review of current weather is required
prior to conducting an approach. Like Part 135 operators,
Part 121 operators are restricted from proceeding past the
FAF of an instrument approach unless the appropriate IFR
landing minimums exist for the procedure. In addition,
descent below the minimum descent altitude (MDA),
decision altitude (DA), or decision height (DH) is governed,
with one exception, by the same rules that apply to Part 91
operators. The exception is that during Part 121 and 135
operations, the airplane is also required to land within the
touchdown zone (TDZ). Refer to the section titled Minimum
Descent Altitude, Decision Altitude, and Decision Height
later in this chapter for more information regarding MDA,
DA, and DH.
Aircraft Performance Considerations
All operators are required to comply with specific airplane
performance limitations that govern approach and landing.
Many of these requirements must be considered prior to the
origination of flight. The primary goal of these performance
considerations is to ensure that the aircraft can remain clear
of obstructions throughout the approach, landing, and go-
around phase of flight, as well as land within the distance
required by the FAA. Although the majority of in-depth
performance planning for an instrument flight is normally
done prior to the aircraft’s departure, a general review of
performance considerations is usually conducted prior to
commencing an instrument approach.
Aircraft Performance Operating Limitations
Generally speaking, air carriers must have in place an
approved method of complying with Subpart I of 14
CFR Parts 121 and 135 (Airplane Performance Operating
Limitations), thereby proving the airplane’s performance
capability for every flight that it intends to make. Flight
crews must have an approved method of complying
with the approach and landing performance criteria in
the applicable regulations prior to departing for their
intended destination. The primary source of information for
performance calculations for all operators, including Part
91, is the approved Aircraft Flight Manual (AFM) or Pilot’s
Operating Handbook (POH) for the make and model of
aircraft that is being operated. It is required to contain the
manufacturer determined performance capabilities of the
aircraft at each weight, altitude, and ambient temperature
that are within the airplane’s listed limitations. Typically, the
AFM for a large turbine powered aircraft should contain
information that allows flight crews to determine that the
aircraft will be capable of performing the following actions,
considering the landing weight and other pertinent
environmental factor:
• Land within the distance required by the regulations.
• Climb from the missed approach point (MAP) and
maintain a specified climb gradient with one engine
inoperative.
• Perform a go-around from the final stage of landing
and maintain a specified climb gradient with all
engines operating and the aircraft in the landing
configuration.
Many airplanes have more than one allowable flap
configuration for normal landing. Often, a reduced flap
setting for landing allows the airplane to operate at a higher
landing weight into a field that has restrictive obstacles in
the missed approach or rejected landing climb path. On
these occasions, the full-flap landing speed may not allow
the airplane enough energy to successfully complete a
go-around and avoid any high terrain and/or obstacles
that might exist on the climb out. Therefore, all-engine
and engine-out missed approaches, as well as rejected
landings, must be taken into consideration in compliance
with the regulations.
Aircraft Approach Categories
Aircraft approach category means a grouping of aircraft
based on a reference landing speed (V REF), if specified, or
if VREF is not specified, 1.3 V SO at the maximum certified
landing weight. V REF, V SO, and the maximum certified
landing weight are those values as established for the
aircraft by the certification authority of the country of
registry. A pilot must use the minima corresponding to
the category determined during certification or higher.
Helicopters may use Category A minima. If it is necessary
to operate at a speed in excess of the upper limit of the
speed range for an aircraft’s category, the minimums for
the higher category must be used. For example, an airplane
that fits into Category B, but is circling to land at a speed of
145 knots, must use the approach Category D minimums.
As an additional example, a Category A aircraft that is
operating at 130 knots on a straight-in approach must use
the approach Category C minimums. See the following
category limits noting that the airspeeds depicted are
indicated airspeeds (IAS):
• Category A: Speed less than 91 knots.
• Category B: Speed 91 knots or more but less than
121 knots.
• Category C: Speed 121 knots or more but less than
141 knots.
• Category D: Speed 141 knots or more but less than
166 knots.
• Category E: Speed 166 knots or more.
Note: Helicopter pilots may use the Category A line of
minimums provided the helicopter is operated at Category
A airspeeds.
An airplane is certified in only one approach category, and
although a faster approach may require higher category
minimums to be used, an airplane cannot be flown to the
minimums of a slower approach category. The certified
approach category is permanent and independent of the
changing conditions of day-to-day operations. From a
TERPS viewpoint, the importance of a pilot not operating
an aircraft at a category line of minimums lower than the
aircraft is certified for is primarily the margin of protection
provided for containment of the aircraft within the
procedure design for a slower aircraft. This includes height
loss at the decision altitude, missed approach climb surface,
and turn containment in the missed approach at the higher
category speeds.
Pilots are responsible for determining if a higher approach
category applies. If a faster approach speed is used that
places the aircraft in a higher approach category, the
minimums for the appropriate higher category must be
used. Emergency returns at weights in excess of maximum
certificated landing weight, approaches made with
inoperative flaps, and approaches made in icing conditions
for some airplanes are examples of situations that can
necessitate the use of higher approach category minima.
Circling approaches are one of the most challenging
flight maneuvers conducted in the NAS, especially for
pilots of CAT C and CAT D turbine-powered, transport
category airplanes. These maneuvers are conducted at
low altitude, day and night, and often with precipitation
present affecting visibility, depth perception, and the ability
to adequately assess the descent profile to the landing
runway. Most often, circling approaches are conducted to
runways without the benefit of electronic navigation aids to
support the descent from the Circling Minimums Decision
Altitude (CMDA) to the runway.
Circling approaches conducted at faster-than-normal,
straight-in approach speeds also require a pilot to
consider the larger circling approach area, since published
circling minimums provide obstacle clearance only
within the appropriate area of protection and is based
on the approach category speed. [Figure 4-2] The circling
approach area is the obstacle clearance area for aircraft
maneuvering to land on a runway that does not meet the
criteria for a straight- in approach. The size of the circling
area varies with the approach category of the aircraft, as
shown in Figure 4-2.
1.3
1.5
1.7
2.3
4.5
Approach category Radius (miles)
RADII (r) defining size of areas, vary
with the approach category
Circling
approach area
Figure 4-2. Construction of circling approach area.
A minimum of 300 feet of obstacle clearance is provided
in the circling segment. Pilots should remain at or above
the circling altitude until the aircraft is continuously in a
position from which a descent to a landing on the intended
runway can be made at a normal rate of descent and using
normal maneuvers. Since an approach category can make
a difference in the approach and weather minimums and,
in some cases, prohibit flight crews from initiating an
approach, the approach speed should be calculated and
the effects on the approach determined and briefed in
the preflight planning phase, as well as reviewed prior to
commencing an approach.
Prior to FAA Order 8260.3 Change 21, pilots were often
faced with the challenge of descending using a stabilized
approach concept if the CMDA height above airport
(HAA) exceeded 1,200 feet. Once the HAA approached
1,200 feet, pilots were often forced to increase their rates
of descent in order to arrive at the appropriate “in-slot”
position. “In-slot” being defined as at a minimum, a CAT C
or CAT D turbine-powered airplane should be wings level
on a three degree - 318 ft/NM descent path not less than 1
NM from the touchdown point (1,000 feet beyond runway
threshold). This was due to the small size of the circling
protected airspace that the aircrews must remain within
to ensure obstacle clearance.
The FAA Order 8260.3 Change 21 to the circling protected
airspace afforded much greater obstacle protection.
However, it also afforded the pilot the opportunity to
use the extra protected airspace to mitigate the need to
conduct a high descent rate, unstabilized approach that
was often necessary as a result of the previous criteria for
the Circling Approach Radius (CAR). For example, under
FAA Order 8260.3 Change 21, a sea level airport with
a 1,500 ft HAA will have CAT C CAR of 2.86 NM, a 1.16
NM (68.5%) increase over pre-Change 21 CAR for CAT C.
This extra protected airspace can be used by the pilot to
maneuver the aircraft instead of being forced to use high
descent rates which are often necessary for high HAA
circling approaches.
Most commercial operators dictate standard procedures for
conducting instrument approaches in their FAA-approved
manuals. These standards designate company callouts,
flight profiles, configurations, and other specific duties
for each flight deck crewmember during the conduct of
an instrument approach.
Instrument Approach Charts
Beginning in February 2000, the FAA began issuing the
current format for instrument approach charts. This chart
was developed by the Department of Transportation
(DOT), Volpe National Transportation Systems Center and
is commonly referred to as the Pilot Briefing Information
format. The FAA chart format is presented in a logical order,
facilitating pilot briefing of the procedures. [Figure 4-3]
Approach Chart Naming Conventions
Individual FAA charts are identified on both the top and
bottom of the page by their procedure name (based on the
NAVAIDs required for the final approach), runway served,
and airport location. The identifier for the airport is also
listed immediately after the airport name. [Figure 4-4]
There are several types of approach procedures that may
cause some confusion for flight crews unfamiliar with the
naming conventions. Although specific information about
each type of approach is covered later in this chapter, listed
below are a few procedure names that can cause confusion.
Straight-In Procedures
When two or more straight-in approaches with the same
type of guidance exist for a runway, a letter suffix is added
to the title of the approach so that it can be more easily
identified. These approach charts start with the letter Z
and continue in reverse alphabetical order. For example,
consider the (RNAV) (GPS) Z RWY 13C and RNAV (RNP) Y
RWY 13C approaches at Chicago Midway International
Airport. [Figure 4-5] Although these two approaches can
be flown with a global positioning system (GPS) to the
Figure 4-3. Instrument approach chart.
010 to 16 DEC 2010 SC-5, 18 NO
NOT FOR NAVIGATION
Figure 4-4. Procedure identification.
same runway, they are significantly different (e.g., one is
a Required Navigation Performance (RNP) Authorization
Required (AR) formally known as SPECIAL AIRCRAFT &
AIRCREW AUTHORIZATION REQUIRED (SAAAR);” one has
circling minimums and the other does not; the minimums
are different; and the missed approaches are not the same).
The approach procedure labeled Z has lower landing
minimums than Y (some older charts may not reflect this).
In this example, the LNAV MDA for the RNAV (GPS) Z RWY
13C has the lowest minimums of either approach due to
the differences in the final approach required obstacle
clearance (ROC) evaluation. This convention also eliminates
any confusion with approach procedures labeled A and
B, where only circling minimums are published. The
designation of two area navigation (RNAV) procedures
to the same runway can occur when it is desirable to
accommodate panel mounted GPS receivers and flight
management systems (FMSs), both with and without
vertical navigation (VNAV). It is also important to note that
only one of each type of approach for a runway, including
ILS, VHF omnidirectional range (VOR), and non-directional
beacon (NDB) can be coded into a database.
Circling-Only Procedures
Approaches that do not have straight-in landing minimums
are identified by the type of approach followed by a letter.
Examples in Figure 4-6 show four procedure titles at the
same airport that have only circling minimums.
As can be seen from the example, the first approach of
this type created at the airport is labeled with the letter A,
and the lettering continues in alphabetical order. Typically,
circling only approaches are designed for one of the
following reasons:
• The final approach course alignment with the
runway centerline exceeds 30°.
• The descent gradient is greater than 400 ft/NM from
the FAF to the threshold crossing height (TCH). When
this maximum gradient is exceeded, the circling
only approach procedure may be designed to meet
the gradient criteria limits. This does not preclude a
straight-in landing if a normal descent and landing
can be made in accordance with the applicable CFRs.
• A runway is not clearly defined on the airfield.
Communications
The communication strip provided near the top of FAA
approach charts gives flight crews the frequencies that
they can expect to be assigned during the approach.
The frequencies are listed in the logical order of use from
arrival to touchdown. Having this information immediately
available during the approach reduces the chances of a
loss of contact between ATC and flight crews during this
critical phase of flight.
It is important for flight crews to understand their
responsibilities with regard to communications in the
various approach environments. There are numerous
differences in communication responsibilities when
operating into and out of airports without ATC towers
as compared to airports with control towers. Today’s
pilots face an increasing range of ATC environments and
conflicting traffic dangers, making approach briefing and
preplanning more critical. Individual company operating
manuals and SOPs dictate the duties for each crewmember.
FAA AC 120-71, Standard Operating Procedures for Flight
Deck Crewmembers, contains the following concerning
ATC communications: SOPs should state who (Pilot Flying
(PF), Pilot Monitoring (PM), Flight Engineer (FE/SO)) handles
the radios for each phase of flight, as follows:
• PF makes input to aircraft/autopilot and/or verbally
states clearances while PM confirms input is what he
or she read back to ATC.
• Any confusion in the flight deck is immediately
cleared up by requesting ATC confirmation.
• If any crewmember is off the flight deck, all ATC
instructions are briefed upon his or her return. Or,
NOT FOR NAVIGATION
EC-3, 18 NOV 2010 to 16 DEC 2010
EC-3, 18 NOV 2010 to 16 DEC 2010
EC-3, 18 NOV 2010 to 16 DEC 2010
EC-3, 18 NOV 2010 to 16 DEC 2010
Figure 4-5. Multiple approaches.